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Biomedical subjects

M Arai

Publications and source records attributed to M Arai.

At least 433 records · Page 24Linked to original sources
PubMed1992

The regulation of calcium cycling in stressed hearts.

Myothermal measurements of tension-independent heat are used to calculate the quantity of calcium released during isometric contraction and the rate at which it is removed in control, thyrotoxic and pressure-overloaded rabbit hearts. Experiments were carried out at 30 degrees C. In control rabbit hearts 41.0 +/- 7.0 nmoles/g Ca++ was released into the cytosol for each beat, while the rate at which the Ca++ was removed from the cytosol was 24.4 +/- 4.4 nmoles/g sec. In the presence-overloaded preparations, the amount of calcium released and the rate of calcium removal were 41% and 40% of control values. This reduction was correlated with the mRNA levels for the sarcoplasmic reticulum (SR) Ca++ ATPase, phospholamban and the ryanodine receptor. The depression was also correlated with a reduction in SR Ca++ ATPase protein expression. In thyrotoxic hearts compared with controls, with each activation there is an increase in the amount of calcium liberated into the cytosol (39%) and the rate of calcium removal (31%). This increase is correlated with an increase in the mRNA and protein expression for the SR Ca++ ATPase as well as the mRNA for the ryanodine receptor. Calsequestrin mRNA was unchanged in all of the experimental preparations. It is suggested that the alteration in the calcium cycling proteins offers at least a partial explanation for the changes in calcium cycling measured in response to the stresses applied.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Ataxic polyneuropathy and anti-Pr2 IgM kappa M proteinemia.

A case of ataxic neuropathy associated with IgM kappa M proteinemia is reported. Double filtration plasmapheresis effectively treated the neuropathy. The IgM kappa antibody had anti-Pr2 cold agglutinin activity. We demonstrated reactivities of the IgM kappa antibody to sialosyl paragloboside, sialosyl lactosaminyl paragloboside, GT1b, GD1a, GD1b, GM3 and GD3 on high-performance thin-layer chromatography immunostaining and enzyme-linked immunosorbent assay, which is previously unreported antigenic specificity of the M proteins in cases of paraproteinemic neuropathy. IgM M protein with anti-Pr2 cold agglutinin activity may play a pathogenetic role in peripheral nerve demyelination, because the target antigens of the M protein are present in myelin and possibly in endothelial cells of the peripheral nervous system.

Ataxia↗
PubMed1992

Thyroid ultrasonography related to clinical and laboratory findings in patients with silent thyroiditis.

We summarized the clinical course of 10 patients with silent thyroiditis and evaluated the clinical usefulness of ultrasonography, in combination with clinical and laboratory findings, for the differentiation from Graves' disease. Serum T3 and T4 were increased in all cases, and the ratio of T3/T4 (ng/micrograms) was 17.8 +/- 3.6 (SD). But in 3 of 10 patients the ratio was greater that 20. TSH receptor antibody (TRAb) and thyroid stimulating antibody (TSAb) were negative in all cases. The estimated thyroid volume by ultrasonography was 18.4 +/- 5.5 ml, which was slightly increased but significantly lower than those in Graves' disease (p less than 0.05). The internal texture of the thyroid showed a decreased echogenicity with a mean echo level of 70.4 +/- 15.4. There was a weak positive correlation between the echo level at the onset of thyrotoxicosis and the lowest T3 level during the clinical course (p less than 0.05). It is suggested that ultrasonography gives a useful information to the diagnosis and outcome of patients with silent thyroiditis.

Adult↗
PubMed1992

Cluster of fibronectin type III repeats found in the human major histocompatibility complex class III region shows the highest homology with the repeats in an extracellular matrix protein, tenascin.

Walking and sequencing a genome portion centromeric of CYP21B in the human MHC class III region disclosed a cluster of fibronectin type III repeats in an approximately 50-kb DNA segment. Fibronectin type III repeats are known to consist of ca. 90 amino acid residues and exist in a wide range of protein species. Homology searches in protein databases showed that the repeats found had the highest homology with the repeats of human tenascin, an extracellular matrix protein. One cDNA sequence located immediately centromeric of CYP21B, the 3' portion of which is transcribed by the opposite strand of CYP21B, was found also to have six type III repeats followed by a fibrinogen domain. Pairwise homology comparison of these repeats in the MHC locus with those of human tenascin showed a general parallelism in their gene organization, indicating that the newly found repeats are elements of certain tenascin-like genea.

Amino Acid Sequence↗
PubMed1992

The influence of argon laser panretinal photocoagulation on the rabbit ERG c-wave.

We observed the influence of panretinal photocoagulation on the ERG c-wave in rabbit eyes. DC-registered ERGs were recorded from rabbit eyes before and after photocoagulation, and compared with those of the fellow eyes. The rabbits were subdivided into 3 groups according to application numbers: 500, 1000, and 1500 spots. The ERG c-waves were found to have totally disappeared in all rabbits 3 days after panretinal photocoagulation, then reappeared with various intervals. In the 500 spot group, the c-wave reappeared after one week, and almost reached control levels in one and a half months. In the 1000 spot group, a 10 day delay was noted, and 90% of control levels were regained after 6 months. In the 1500 spot group, the c-wave didn't reappear until 2 weeks later, and regained 70% (of the control level) after 6 months. The recovery rates were related to the number of laser applications. These results indicate that the ultimate degree of recovery in c-wave amplitude and the time required for the reestablishment of retinal pigment epithelium function both depend on the size of the coagulated area.

Animals↗
PubMed1992

Structural identification of an epitope of antigenic factor 5 in mannans of Candida albicans NIH B-792 (serotype B) and J-1012 (serotype A) as beta-1,2-linked oligomannosyl residues.

In previous articles, we reported the presence of phosphate-bound beta-1,2-linked oligomannosyl residues in the mannans of strains of Candida albicans serotypes A and B and Candida stellatoidea. To identify the antigenic factor corresponding to this type of oligomannosyl residue, a relationship between chemical structure and antigenic specificity in the mannans of C. albicans NIH B-792 (serotype B, B-strain) and C. albicans J-1012 (serotype A, J-strain) was investigated by using a combination of two-dimensional 1H nuclear magnetic resonance spectroscopy of H-1, H-2, and H-5 regions in the mannans and an enzyme-linked immunosorbent assay that employed concanavalin A-coated microtiter plates. It was shown in the present 1H nuclear magnetic resonance study that an examination of chemical shifts not only in the H-1 region but also in the H-5 region was useful for the quantitative determination of the phosphate-bound beta-1,2-linked oligomannosyl residues. In the enzyme-linked immunosorbent assay using concanavalin A-coated plates, it was revealed that, of factor sera 1, 4, and 5, only factor serum 5 showed a reactivity proportional to the densities of the beta-1,2-linked oligomannosyl residues of the mannan subfractions of different phosphate contents that had been prepared from the bulk B-strain mannan by DEAE-Sephadex chromatography. The above results indicate that the phosphate-bound beta-1,2-linked oligomannosyl residues, Manp beta 1----(2Manp beta 1----)n2Man (n = 0-5), correspond to antigenic factor 5.

Antigens, Fungal↗
PubMed1992

Regulation of sarcoplasmic reticulum gene expression during cardiac and skeletal muscle development.

The expression of major sarcoplasmic reticulum proteins during cardiac and fast-twitch skeletal muscle development was examined using gene-specific probes. Through the use of S1 nuclease mapping, Northern blot, and RNA slot-blot analysis, sarcoplasmic reticulum proteins were shown to exhibit both narrow tissue specificity and plasticity in their expression during muscle development. In fast-twitch skeletal muscle, the cardiac/slow-twitch isoforms of Ca(2+)-ATPase and calsequestrin were detected at high levels in fetal stages but were gradually replaced by fast-twitch isoforms in adult muscle. In contrast, cardiac muscle expressed exclusively cardiac/slow-twitch isoforms of Ca(2+)-ATPase and calsequestrin at all stages. Both fast-twitch and slow-twitch skeletal muscle expressed the same skeletal muscle ryanodine receptor isoform, whereas cardiac muscle expressed a cardiac isoform. Phospholamban expression was restricted to cardiac and slow-twitch skeletal muscle and did not appear in developing fast-twitch skeletal muscle. During in vitro myogenesis of C2C12 cells, the mRNA transcripts encoding sarcoplasmic reticulum proteins were found to be coordinately induced in synchrony with that of contractile protein mRNA. The myogenic factor "myogenin" induced sarcoplasmic reticulum gene transcripts along with contractile protein mRNAs in nonmyogenic cells. These data suggest that the induction of both sarcoplasmic reticulum and contractile protein gene families is under the control of a common myogenic differentiation program.

Actins↗
PubMed1992

Cysteamine enhances the procoagulant activity of Factor VIII-East Hartford, a dysfunctional protein due to a light chain thrombin cleavage site mutation (arginine-1689 to cysteine).

We have recently identified the molecular defect responsible for cross-reacting material-positive hemophilia A in two unrelated patients in which the substitution of cysteine for arginine-1689 (Factor VIII-East Hartford[FVIII-EH]) abolishes a critical Factor VIII light chain thrombin cleavage site. As other mutant proteins with a cysteine for arginine substitution have been modified in the presence of cysteamine, we have determined the effect of this and other reducing agents on FVIII-EH function. Cysteamine concentrations between 0.1 and 10 mM caused dose- and time-dependent increases in FVIII-EH VIII:C activity, as much as 14-fold (to 35 and 62 U/dl for the two patients tested). Comparable data were obtained in a standard one-stage VIII:C coagulation assay and in a chromogenic substrate assay measuring Factor Xa generation. Thrombin cleavage of the FVIII-EH light chain in the presence of cysteamine was documented by immunoadsorption and analysis. Cystamine and cysteamine-S-phosphate, similar compounds that do not possess a free thiol group, had no effect. Cysteamine augmentation of FVIII-EH VIII:C was abolished by the simultaneous addition of N-ethyl maleimide or iodoacetamide, but these sulfhydryl blocking agents did not prevent the VIII:C increase and light chain cleavage by thrombin if the plasma samples were dialyzed to remove the inhibitors before adding the cysteamine. However, incubation with DTT before iodoacetamide prevented the cysteamine effect after dialysis. These data suggest that when isolated from patient plasma, FVIII-EH cysteine-1689 is present in a disulfide bond. This bond is cleaved by cysteamine to form a new mixed disulfide, a pseudolysine that restores a thrombin cleavage site that is essential for procoagulant function.

Blood Coagulation↗
PubMed1992

[Effects of vanadyl sulfate on osteopenia in streptozotocin-induced diabetic (STZD) rats. Comparison with those of insulin].

The insulin mimetic effects of vanadium salts on glucose metabolism have been well-documented in STZD rats. In this study, the long-term effects of vanadyl sulfate (vanadium) on osteopenia in STZD rats were examined and compared with those of insulin. From 2 days after an intravenous injection of streptozotocin (30 mg/kg), the rats with hyperglycemia (> 300 mg/dl) received either vanadium (0, 0.02, 0.1 or 0.5 mg/ml) in drinking water or daily subcutaneous injections of insulin (0, 0.4 or 4.0 U/day) for 54 days. Their tibiae and femurs were examined by chemical analyses, by contact microradiography and by the method of double tetracycline labeling. Decreases in bone mass, bone density and in the rate of bone formation were observed in STZD rats. Development of these symptoms in the STZD rats with osteopenia was prevented by the administration of either vanadium or insulin in a dose-dependent fashion. The effects of vanadium at a dose of 0.5 mg/ml for preventing bone loss in STZD rats were similar to those of insulin at a dose of 4.0 U/day. These results indicate that vanadium has insulin mimetic effects on osteopenia in STZD rats.

Animals↗
PubMed1992

Purification and some properties of a Haim-sensitive alpha-amylase from newly isolated Bacillus sp. No. 195.

Newly isolated Bacillus sp. No. 195 produced an extracellular alpha-amylase sensitive to Haim which was found to inhibit specifically animal alpha-amylases. The enzyme was purified easily by two steps of starch adsorption and gel filtration using Sephacryl S-200. The purified enzyme, which showed a single band on native-PAGE or SDS-PAGE, had a molecular weight of 60,000 as judged on SDS-PAGE. The optimum pH value for activity and the isoelectric point were around 7.0 and 4.5, respectively. The sensitivity of the amylase to Haim was similar to that of animal amylase rather than bacterial amylase. It was suggested that a Haim-amylase complex might be formed at the molar ratio of 1:1. The amino acid sequence F-S-W similar to the triplet F-E-W highly conserved among alpha-amylases sensitive to proteinaceous inhibitors, such as Hoe 467-A or Haim, was found in the amino-terminal part of the No. 195 amylase.

Amino Acid Sequence↗
PubMed1992

A case of autoimmune insulin antibody syndrome associated with polymyositis, empty sella and apparent high urinary output of immunoreactive insulin.

Patients with autoimmune insulin antibody are characterized by hypoglycemic attacks and antibodies to insulin in serum without prior insulin administration. In the present report, a patient with hypoglycemia due to autoimmune insulin antibody associated with primary empty sella syndrome and polymyositis appeared to have high urinary immunoreactive insulin (IRI) in the face of normal urinary C peptide. Consequently, the urinary IRI/C peptide ratio was apparently high. The amelioration of hypoglycemic attacks and polymyositis by prednisolone treatment was accompanied by the disappearance of the antibodies and complete normalization of the urinary IRI and IRI/C peptide ratio. No comparable rise in the urinary IRI and IRI/C peptide ratio was observed in the patients with other disorders studied. Glucose clamp and glucose tolerance study showed decreased sensitivity to exogenous or newly secreted insulin, prolonged half disappearance time of serum insulin, and normal disappearance of blood glucose. These results were consistent with the idea that autoantibodies buffered the effect of exogenous or newly secreted insulin and maintained a relatively constant level of serum free insulin which was not high enough when a large amount of glucose was loaded, but was too high after prolonged fasting, which eventually caused hypoglycemic attacks.

Autoantibodies↗
PubMed1992

Synovial fluid ferritin in traumatic hemarthrosis, rheumatoid arthritis and osteoarthritis.

Synovial fluid ferritin levels in patients with traumatic hemarthrosis (HA), rheumatoid arthritis (RA), and osteoarthritis (OA) were measured by double antibody radioimmunoassay. Synovial fluid ferritin levels were significantly higher in 60 patients with HA (mean +/- S.D., 536 +/- 536 ng/ml) and 39 patients with RA (614 +/- 486 ng/ml) than in 20 patients with OA (130 +/- 119 ng/ml) (p < 0.01). Individual levels, however, considerably varied. In HA patients, the synovial fluid ferritin level correlated well with the duration of hemarthrosis, but not with hemoglobin, hematocrit, or an inflammatory synovial fluid index such as the leukocyte count. In RA patients, there was no significant correlation between the synovial fluid ferritin levels and any inflammatory parameter, such as catalase activity, synovial leukocyte counts (including polymorphs and monocytes) or the duration of arthritis. Our results indicate that the synovial fluid ferritin level reflects primarily hemoglobin degradation and appears unrelated to inflammation in joint diseases.

Adolescent↗
PubMed1992

Herpes simplex virus type 1 and human immunodeficiency virus type 1 antigens in platelets from a hemophilia B patient with human immunodeficiency virus type 1-related thrombocytopenia.

We analyzed platelet-associated antigens from a hemophilia B patient with human immunodeficiency virus type 1 (HIV-1)-related thrombocytopenia. Two bands appeared at 31,000 and 37,000 daltons in the platelet lysate after reaction with autologous serum in SDS-PAGE and Western blots. The band at 37,000 daltons was obtained using anti-herpes simplex type 1 (HSV-1) rabbit antiserum. Doublet bands at 36,000 and 37,000 daltons also appeared after reaction with HSV-1 seropositive human serum. The band at 31,000 daltons appeared after reaction with anti-HIV-1 rabbit serum. These results suggest that the platelet-associated antigens in this patient are components of both HSV-1 and HIV-1 antigens. In addition, acyclovir decreased his PAIgG level and increased his platelet count, and zidovudine increased his platelet count. Thus, we concluded that each of the platelet-associated antigens is partially responsible for the thrombocytopenia by causing deposition of immune complexes in this patient.

Acyclovir↗
PubMed1992

Mesangial cell growth in genetically hypertensive rats and effect of calcium antagonists upon this growth.

Mesangial cells play an important role in physiological and pathophysiological regulation of glomerular functions. To explore the involvement of deranged mesangial cell functions in the pathogenesis of hypertension, the growth activity of mesangial cells was compared in stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto rats (WKY). Upon exposure to fetal calf serum, the growth rate was significantly higher in mesangial cells cultured from glomeruli of 4-week old SHRSP than in those of age-matched WKY. This abnormally high growth of SHRSP mesangial cells was significantly inhibited by dihydropyridine calcium antagonists. Of the three antagonists tested, manidipine was the most potent inhibitor. Significant growth inhibition occurred at a concentration as low as 10(-12) M; inhibition as high as 65% was found at 10(-6) M. Calcium antagonists, particularly manidipine, may prevent or delay the development of hypertension not only through vasodilation but also through inhibition of mesangial cell growth. By slowing mesangial cell proliferation, calcium antagonists also may slow the progression of hypertension-induced glomerular sclerosis.

Animals↗
PubMed1992

Purification and characterization of the HPR protein of Pediococcus halophilus.

HPr protein, the ptsH gene product, of the phosphoenolpyruvate:sugar phosphotransferase system of Pediococcus halophilus was purified to homogeneity using heat and acid treatments, DEAE-Sepharose CL-6B and hydroxyapatite column chromatographies. The purified protein complemented the HPr activity of the phosphotransferase system in Staphylococcus aureus ptsH mutant cell lysate. The molecular weight was estimated as 6,500 by SDS polyacrylamide gel electrophoresis. The amino acid sequence of the amino-terminal part (1-44) of the native purified protein was highly homologous to those of HPr proteins from gram-positive bacteria. Antiserum raised against the purified HPr protein specifically reacted with the Pediococcus halophilus HPr protein and did not cross-react with Staphylococcus aureus or Escherichia coli HPr proteins.

Amino Acid Sequence↗
PubMed1992

[Bilateral distal anterior cerebral artery aneurysms associated with polycystic kidney and liver disease; a case report].

A patient who had bilateral distal anterior cerebral artery aneurysms and a right middle cerebral artery aneurysm in association with polycystic kidney and liver disease is reported. A 57-year-old woman was referred to our center with headache and disturbance of consciousness. On admission, her level of consciousness as evaluated by the Japan Coma Scale was 10. CT revealed subarachnoid hemorrhage, especially in the interhemispheric fissures. Right carotid angiography demonstrated bilateral distal anterior cerebral artery aneurysms and a right middle cerebral artery aneurysm. All three aneurysms were clipped in a one-stage procedure. The patient was discharged without any neurological deficits two weeks after the operation. Bilateral distal anterior cerebral artery aneurysms are extremely rare. This is the first report of such aneurysms and a right middle cerebral artery aneurysm in association with polycystic kidney and liver disease. The etiology of these aneurysms is discussed.

Cerebral Angiography↗